Airbags generally provide vehicle occupant protection. Regardless of the application, airbags generally have the common feature of distributing inflation gases quickly into the inflatable portions of the airbag cushion. This distribution and filling the airbag can be more or less difficult depending on the shape of the airbag being deployed. One example of a more complex inflation challenge is side curtain airbags (also referred to herein as a curtain airbag).
The side curtain airbag assembly provides protection of the vehicle occupants along the sides of the vehicle, more particularly from the roof down across the door windows and pillars. On deployment a gas generating inflator is activated to fill inflatable chambers of the bag. As the length of a vehicle can vary the overall length of the airbag similarly can be great. For the inflator to properly fill the airbag, the inflator is often placed close to the middle of the bag so gas can flow from the center outwardly toward both ends. One way to enhance uniform distribution of the inflation gases is to provide a fabric diffuser which receives the nozzle end of a cylindrical inflator and simultaneously distributes the inflation gases in a generally forward and rearward direction to more quickly and uniformly fill the inflatable chambers along the length of the curtain airbag. Such a curtain airbag is described in U.S. Pat. No. 7,789,418 entitled “Curtain Airbag Assembly,” the subject matter of which is hereby incorporated by reference in its entirety.
During the manufacture of the curtain airbag, fabric is sewn and stitched together or woven to form a side curtain airbag with inflatable chambers, non-inflatable regions, gas flow channels and border or perimeter seams. These border or perimeter seams provide anchoring locations to secure the curtain airbag to the vehicle.
In the airbag there is provided an inlet opening for receiving a fill tube connected to an inflator or an inflator is placed at least partially into the inlet and the inlet is clamped about the body of the inflator with the gas discharging nozzle end sealed inside the cushion at the clamped inlet. Preferably, this inlet for the inflator can be made part of an internally located fabric diffuser. The diffuser has the inlet opening and a small discharge chamber with at least one, but preferably two gas discharge openings as shown in prior art FIG. 1 of U.S. Pat. No. 7,789,418; this prior art diffuser had one circular gas discharge opening in the fabric panel for this purpose. In a more preferred embodiment, a prior art diffuser is shown in prior art FIG. 2 having two gas discharge openings. The directionally opposite facing opening allows inflation gas to escape fore and aft to rapidly fill the cushion along its length as it deploys. One concern of this prior art diffuser was its ability to absorb the high pressure of inflation without tearing. In order to keep the diffuser intact, it was proposed to fold the panels of the diffuser over using one or more panels sewn together in various regions forming seams.
While this diffuser was a good improvement over the earlier prior art, it was limited in the amount of pressure it could withstand at the seam joints, most particularly at the upper perimeter seam joints attaching the diffuser to the airbag. While the folded seamless portion afforded good peak pressure survivability, it was believed even this diffuser could be improved in terms of structural integrity when exposed to very high inflation pressures. More importantly, if the diffuser strength could be increased, more aggressive inflation could be used to decrease deployment and fill times.
While this prior art curtain airbag example is one having a difficult inflation requirement, it is important to note it is merely an example and many other types of airbags can benefit by improved bag structures and design that can withstand rapid high peak inflation pressure and improved inflation gas distribution.
These and other improvements are found in the invention described as follows.